ESCANABA, Mich., Oct. 11 (UPI) — A 600-foot-long fissure that opened in the ground in Michigan may be the result of fractured rock deep below the surface, a state official says.

When the fissure erupted last week in Menominee County, local residents reported feeling vibrations and hearing a loud bang, with one neighbor comparing the sound to blasting, the Daily Press of Escanaba (Mich.) reported.

The fissure was discovered when a resident went into the local woods to cut a pine tree, the newspaper said.

An official said the phenomenon is not unusual in the state’s Upper Peninsula.

“There are fractured rock formations in some areas of the Upper Peninsula, and where there are these fractured rock formations, fissures such as the one described occur,” said Rory Mattson, executive director of the Delta Conservation District in Gladstone.

In areas where there are fractured rock formations, the annual freeze-thaw creates pressure and can lead to the formation of fissures or even sink holes, he said.

It was the release of the pressure that would have sounded very much like an explosion or someone blasting nearby, he said.